Capillary electrophoresis of nonprotein and protein amino acids without derivatization

• Published in: Electrophoresis 2000-03, Vol.21 (5), p.930-934
• Main Authors: Lee, Jin Hee, Choi, One-Kyun, Jung, Hee Su, Kim, Kyoung-Rae, Chung, Doo Soo
• Format: Article
• Language: English
• Subjects: Amino Acids - isolation & purification; Buffers; Capillary electrophoresis; Electrophoresis, Capillary - methods; Hydrogen-Ion Concentration; Isoelectric Point; Large volume stacking; Nonprotein amino acid; Osmolar Concentration; Phosphates; Proteins - analysis; Sensitivity and Specificity; Stacking
• ISSN: 0173-0835; 1522-2683
• DOI: 10.1002/(SICI)1522-2683(20000301)21:5<930::AID-ELPS930>3.0.CO;2-8

An efficient separation of eleven nonprotein amino acids (NPAAs) and three protein amino acids containing aromatic moieties was achieved by capillary electrophoresis without derivatization. The fourteen amino acids were well separated with a 100 mM sodium phosphate run buffer (pH 2.0) using a 57 cm fused‐silica capillary (50 μm ID, 50 cm effective length) at 20°C. With an electric field of 351 V/cm, the time needed for the separation was less than 20 min. Under optimum conditions, excellent linear responses were obtained in the concentration range of 5—100 μM, with the linear correlation coefficient ranging from 0.9785 or greater. The relative standard deviations of the migration times and the corrected peak areas were found to be 1.5—3.9% and 8.0—11.5%, respectively. In order to improve the limit of detection (LOD), simple stacking and large volume stacking using an EOF pump (LVSEP) methods were used. Improved LODs were about 300 nM in stacking and below 15 nM for five small NPAAs in LVSEP.